Electric timepiece

ABSTRACT

An electric timepiece which uses an electrically driven balance wheel oscillator as time standard, the latter being connected to the circuitry by two spring elements. One of these spring elements is provided with a device to adjust its elasticity in order to change the oscillator frequency. This vary one of the two elastic elements is permanently connected to a bridge carrying a balancing bearing and being insulated from the other part of the movement and serving as connection to the circuitry. The other spring means is in permanent electrical connection with the frame plate of the movement.

United States Patent [191 Meitinger 1 Oct. 22, 1974 1 ELECTRIC TIMEPIECE 21 Appl. No.: 305,072

[30] Foreign Application Priority Data Nov. 30, 1971 Germany 2159190 [52] US. Cl. 58/28 B, 58/23 R. 310/36 [51] Int. Cl. G04b 29/00 [58] Field of Search 58/28 B, 28 D, 23 R, 23 A, 58/23 D, 23 V, 28 R, 52 R, 52 A, 116 R, 116 M, 107, 109, 117; 318/128, 132; 310/15, 36

[56] References Cited UNITED STATES PATENTS 2,948,821 8/1960 Van Horn cl :1]. 58/28 B 3.186.157 6/1965 Favrct ct a1. 58/28 B 3,528,237 9/1970 Suard 58/23 R FOREIGN PATENTS OR APPLICATIONS 501,215 4/1920 France 58/28 B Primary ExaminerRichard B. Wilkinson Assistant ExaminerU. Weldon Attorney, Agent, or FirmH. Dale Palmaticr; James R. Haller 57] ABSTRACT An electric timepiece which uses an electrically driven balance wheel oscillator as time standard, the latter being connected to the circuitry by two spring elements. One of these spring elements is provided with a device to adjust its elasticity in order to change the 0scillator frequency. This vary one of the two elastic elements is permanently connected to a bridge carrying a balancing bearing and being insulated from the other part of the movement and serving as connection to the circuitry. The other spring means is in permanent electrical connection with the frame plate of the movement.

8 Claims, 2 Drawing Figures mimiuwzz 8.842.888

SHEET 1 0F 2 Fig. 1

ELECTRIC TIMEPIECE BACKGROUND OF THE INVENTION Electric timepieces are known which are driven as a result of the interaction of movable coils positioned on the balance wheel, with stationary magnets.

The said timepieces necessitate two spring elements, mostly hairsprings, for the supple of current to the coils. The existence of such two constituent elements is inevitable, above all in timepieces that are fitted with electric switching circuits as they necessitate a permanent electrical connection between the electric switch ing circuit and the driving coils. The necessity of such two constituent elements is considered to be the main disadvantage of the electric drive with movable coils. The connection between the spring element insulatedly positioned on the balance staff and the electric switching circuit is established by special devices, especially clamping devices, that are themselves connected to the electric switching circuit. For the sake of completeness it must be mentioned that another system is known where the driving magnets instead of the coils are arranged on the balance wheel. It is obvious that the driving coils can easily be connected to the electric switching circuit in the said system with stationary coils. The system with movable coils has the advantage, however, that firstly, an interference caused by external magnetic fields need not be feared and secondly, the movable coil occupies less room thanthe relatively large magnets. Thus, the movable coil is better suited to small-sized timepieces, especially to ladies wristwatches.

SUMMARY OF THE INVENTION In order to obviate the disadvantages of the two spring elements for electric timepieces with movable coils, according to the instant invention, the said two spring elements are according to the presented invention, housed in such a way that no supplementary components are required for their stationary connection, and that the two spring elements do not influence the size of the timepiece movement.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 show an embodiment of the above invention. Other advantages will be apparent from the following detailed description of the invention used in conjunction with the accompanying drawings, in which:

FIG. 1 is a sectional view showing the arrangement of balance wheel 17 with spring elements and 20.

FIG. 2 is a top view showing the insulated bridge 3 as well as its mounting elements and regulator FIG. 9 with spring element 10 and 20.

DETAILED DESCRIPTION OF THE INVENTION As illustrated in FIG. 1, pillar 24 is in frame plate 8. Train wheel bridge 5 is positioned on said pillar 24. The magnet system with shunt plates 19 and and magnets 18 and 16 is between frame plate 8 and train wheel bridge 5. Balance wheel 17 with driving coils 33 is positioned in the airgap between magnets 18 and 16. Below shunt plate 19 there is spring element 20 bonded together with frame plate 8 and positioned on balance staff 12 together with hairspring hub 21. Balance staff 12 is pivoted in frame plate 8, so that balance wheel 17 can execute torsional vibrations in the known way. Above balance wheel 17 there is roller 13 which is electrically separated from balance staff 12 by means of insulating portion 14.

On the roller 13 there is the hairspring hub 11 to which the inner tail of spring element 10 is attached. The outer tail of spring element 10 is fixed to protrusion 25 of bridge 3 carrying a balance bearing and being positioned in an electrically insulated manner on the movement frame. Regulator 9 is pivoted coaxially with balance staff 12 on the insulated bridge 3. The effective length of spring element 10 and therefore the oscillation frequency of balance wheel 17, can be changed by means of said regulator 9. Insulated bridge 3 rests on insulating portion 4 which lies directly on train wheel bridge 5. Insulated bridge 3 as well as train wheel bridge 5 and insulating portion 4 are held on the movement frame by means of screws 7. Insulating washer 6 is positioned between screws 7 and insulated bridge 3. Said insulating washer 6 electrically insulates screws 7 from insulated bridge 3. Disk 27 is positioned on balance staff 12; said disk 27 carrying pin 22, the latter cooperating with fork 23 of the index lever not shown, which takes over the mechanical motion from balance wheel 17. With its circumference 29 positions insulated bridge 3 as well as insulating portion 4 on the movement frame by means of holes 31 which are concentrically arranged above holes 30 that are located in train wheel bridge 5. FIG. 1 furthermore shows coils 33 of which one is connected to roller 13 by wire 34 and which are connected together by wire 35. One of these coils is connected to balance staff 12 and herewith to spring element 20 by wire 36. Said figure also shows schematically the electric driving circuit 37 which is connected to insulated bridge 3 and frame plate 8. The outer turn of spring element 20 is positioned in an electrically conductive manner in frame plate 8. Insulated side 32 which is opposite to the side of the timepiece carrying the time indication means and being called the dial side. The time indication means are later on positioned in the plane of carrier 2 which is removed as soon as screws 7 have been tightened and pins 1 are no longer needed.

FIG. 2 is a top view of the arrangement according to FIG. 1 with spring element 28 serving as connection with the electric driving circuit and resting with spring pressure against the insulated bridge 3. In the presented top view only the external turn of spring element 10 is represented.

In comparison with known arrangements the system described above has the advantage that firstly, no additional component for connecting spring element 10 insulatedly positioned on balance staff 12, with the electric driving circuit is required as for this purpose the already available insulated bridge 3 is made use of. Considering the fact that insulated bridge 3 can be designed in a very simple manner, especially when being constructed as a flat component, there is the possibility of connecting insulated bridge 3 to the electric driving circuit in a simple way. As insulated bridge 3 itself is connected to insulated spring element 10, it is also possible to influence the effective length of spring element 10 by means of regulator 9 that is likewise positioned on insulated bridge 3. The reason why the insulated bridge 3 is positioned on the movement side turned away from the dial side is that insulated spring element 10 is likewise positioned on the movement side contrary to the position of spring element 20 being bonded together with frame plate 8. As spring element 20 on the dial side of spring element 10 needs no longer be insulated from balance staff 12, it is now possible to arrange the spring element 20 between index lever fork 23 and frame plate 8 without fearing an electrical short-circuit when a physical contact is made between balance staff 12 and index lever fork 23. When positioning spring element 20 between index lever fork 23 and frame plate 8, spring element 20 thus occupies a place in the timepiece movement that is not used for other components and cannot be used for them, respectively. As this said space until now unused, can be employed for second spring element 20, said spring element 20 does not cause any increase in the overall height of the timepiece. This point of view is of great importance, especially in the case of wrist-watches. As dial-sided spring element 20 is also inside frame plate 8, it is possible to fasten this spring element 20 in a simple way by devices provided for on frame plate 8. Positioning of insulated bridge 3 can be made in the known way by pins 1 being fastened in train wheel bridge 5. Said pins 1 should be of electrically non-conducting material in order to guarantee electrical insulation between train wheel bridge 5 and insulated bridge 3. As the available plastics are considerably softer than metallic materials, positioning by means of plastics would be relatively unsafe. Secure positioning could only be reached by pins of ceramic materials, especially synthetic jewels. As synthetic jewels are relatively expensive, positioning can also be made by metallic pins, as shown in FIG. 1. Said metallic pins are mounted on a carrier 2 and inserted until screws 7 are tightened. As insulated bridge 3 can no longer be moved after the tightening process of screws 7, metallic pins 1 can then be removed.

Considering the fact that the two spring elements 10 and 20 are positioned on opposite sides of the timepiece movement, there is furthermore the advantage that they are shielded from magnets 16 and 18 by shunt plates and 19. Besides, said shunt plates 15 and 19 also shield spring elements 10 and 20 from the other components. The two spring elements 10 and 20 themselves are safely separated from each other because of the spatial distance. In the case of the known arrangements where the spring elements are arranged either at a short distance from each other or in the plane of the driving magnets, there is the risk that the spring elements may be caught in one another or in other components of the movement and so cause the timepiece to stop running. In the case where the spring elements are housed in the plane of the magnets, the spring elements are influenced by the stray magnetic fields. lt is then necessary to make the said spring elements of nonmagnetic material which means that the temperature compensated material Nivarox cannot be used.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The embodiment disclosed is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims.

I claim:

1. In an electric timepiece,

a rotatably oscillatable balance wheel movable about an axis and having a coil thereon,

magnet means located adjacent the balance wheel and adjacent the coil,

means mounting said magnet means and including a frame plate,

a rotatably oscillatable balance staff having first and second ends and having the same axis as said balance wheel and mounting the balance wheel for oscillation therewith, the first end of the balance staff being rotatably carried by the frame plate,

an electric driving circuit to control the current to said coils and being connected to the frame plate,

a hairspring hub encompassing the balance staff, and conductive connecting means insulated from the balance staff securing the hairspring hub to the balance staff for rotable oscillation therewith,

conductors respectively connecting the coil to the balance staff and to said conductive connecting means for connection to said hairspring hub,

a first hairspring encompassing the balance staff and means connecting one end of the hairspring to the balance staff, the other end of the hairspring being connected to the frame plate to thereby provide electrical continuity from the driving circuit and frame plate, to the balance staff, coil and hub,

a rigid bearing bridge confronting the frame plate in fixed relation therewith and rotatably carrying the second end of the balance staff, the bearing bridge also being connected to said driving circuit,

means mounting the bearing bridge in fixed relation to the frame plate and in electrically insulating relation thereto,

a second hairspring encompassing the balance staff and having one end connected to the hairspring hub,

and means securing the other end of the second hairspring to the bearing bridge for completing electrical continuity from the hub and spring to the bearing bridge and driving circuit for supplying current to the coil.

2. The invention set forth in claim 1 and also including an adjustable regulator on the bearing bridge and engaging the second hairspring for varying the effect of said hairspring upon the balance staff and the balance wheel.

3. The invention set forth in claim 1 wherein the timepiece has opposite sides including the movement side and the dial side, said frame plate being disposed adjacent the dial side, and said rigid bearing bridge disposed adjacent the movement side.

4. The invention set forth in claim 1 and including means transmitting the physical oscillatory movement from the balance wheel and including a pin and fork, said pin and fork being disposed adjacent said first hairspring, the balance wheel being disposed between the second hairspring and said pin and fork whereby to avoid any possible interference between said second hairspring and the pin and fork.

5. The invention set forth in claim 1 and said magnet mounting means including a pair of shunt plates affixed between and confronting the frame plate and bearing bridge adjacent the balance wheel, said first and second hairsprings being disposed between said shunts and, respectively, the frame plate and the bearing bridge, said magnet means including a plurality of magnets mounted on said shunt plates and disposed between said shunt plates and adjacent the balance wheel.

6. The invention according to claim 1 and said bearing bridge comprising a fiat plate confronting the frame plate and confining the balance wheel, balance staff, and springs therebetween.

7. The invention according to claim 1 and including an insulating foil positioned between said rigid bearing bridge and said means mounting the bearing bridge.

8. In an electric timepiece,

a frame plate,

a rigid bearing bridge confronting said frame plate in fixed relation thereto,

means mounting the bearing bridge in fixed relation to the frame plate and in electrically insulating relation thereto,

electric driving circuit means interconnecting said bearing bridge and said frame plate,

a balance wheel and a balance staff carrying the balance wheel and mounted between said frame plate and bearing bridge and including a coil on the balance wheel, one side of the coil being connected to the balance staff, and the other side of the coil being connected to a spring hub insulated from the balance staff,

and a pair of hairsprings, one being connected between the balance staff and the frame plate, and the other of the hairsprings being connected between the insulated hub and the bearing bridge to provide electrical continuity between the coil and the electric driving circuit. 

1. In an electric timepiece, a rotatably oscillatable balance wheel movable about an axis and having a coil thereon, magnet means located adjacent the balance wheel and adjacent the coil, means mounting said magnet means and including a frame plate, a rotatably oscillatable balance staff having first and second ends and having the same axis as said balance wheel and mounting the balance wheel for oscillation therewith, the first end of the balance staff being rotatably carried by the frame plate, an electric driving circuit to control the current to said coils and being connected to the frame plate, a hairspring hub encompassing the balance staff, and conductive connecting means insulated from the balance staff securing the hairspring hub to the balance staff for rotable oscillation therewith, conductors respectively connecting the Coil to the balance staff and to said conductive connecting means for connection to said hairspring hub, a first hairspring encompassing the balance staff and means connecting one end of the hairspring to the balance staff, the other end of the hairspring being connected to the frame plate to thereby provide electrical continuity from the driving circuit and frame plate, to the balance staff, coil and hub, a rigid bearing bridge confronting the frame plate in fixed relation therewith and rotatably carrying the second end of the balance staff, the bearing bridge also being connected to said driving circuit, means mounting the bearing bridge in fixed relation to the frame plate and in electrically insulating relation thereto, a second hairspring encompassing the balance staff and having one end connected to the hairspring hub, and means securing the other end of the second hairspring to the bearing bridge for completing electrical continuity from the hub and spring to the bearing bridge and driving circuit for supplying current to the coil.
 2. The invention set forth in claim 1 and also including an adjustable regulator on the bearing bridge and engaging the second hairspring for varying the effect of said hairspring upon the balance staff and the balance wheel.
 3. The invention set forth in claim 1 wherein the timepiece has opposite sides including the movement side and the dial side, said frame plate being disposed adjacent the dial side, and said rigid bearing bridge disposed adjacent the movement side.
 4. The invention set forth in claim 1 and including means transmitting the physical oscillatory movement from the balance wheel and including a pin and fork, said pin and fork being disposed adjacent said first hairspring, the balance wheel being disposed between the second hairspring and said pin and fork whereby to avoid any possible interference between said second hairspring and the pin and fork.
 5. The invention set forth in claim 1 and said magnet mounting means including a pair of shunt plates affixed between and confronting the frame plate and bearing bridge adjacent the balance wheel, said first and second hairsprings being disposed between said shunts and, respectively, the frame plate and the bearing bridge, said magnet means including a plurality of magnets mounted on said shunt plates and disposed between said shunt plates and adjacent the balance wheel.
 6. The invention according to claim 1 and said bearing bridge comprising a flat plate confronting the frame plate and confining the balance wheel, balance staff, and springs therebetween.
 7. The invention according to claim 1 and including an insulating foil positioned between said rigid bearing bridge and said means mounting the bearing bridge.
 8. In an electric timepiece, a frame plate, a rigid bearing bridge confronting said frame plate in fixed relation thereto, means mounting the bearing bridge in fixed relation to the frame plate and in electrically insulating relation thereto, electric driving circuit means interconnecting said bearing bridge and said frame plate, a balance wheel and a balance staff carrying the balance wheel and mounted between said frame plate and bearing bridge and including a coil on the balance wheel, one side of the coil being connected to the balance staff, and the other side of the coil being connected to a spring hub insulated from the balance staff, and a pair of hairsprings, one being connected between the balance staff and the frame plate, and the other of the hairsprings being connected between the insulated hub and the bearing bridge to provide electrical continuity between the coil and the electric driving circuit. 